High-efficiency magnetron



I April 1951 P. L SPENCER 3, 2,550,614

HIGH-EFFICIENCY MAGNETRON Filed Nov; 13, 1942 2'Sheets-Sheet 2 Patented Apr. 24, 1951 HIGH-EFFICIENCY MAGNETRON Percy L. Spencer, West Newton, Mass, assignor to Raytheon Manufacturing Company, Newton, Mass, a corporation of Delaware Application November 13, 1942, semi No. 465,413

37 Claims.

This invention relates to a magnetron and more particularly to one which has a plurality of possible oscillatingmodes, each determined primarily by the geometry of the internal struc ture of the magnetron. A device of this kind is intended to oscillate in a predetermined principal mode so as to generate a predetermined frequency. Heretofore difliculties have been en countered in that additional modes of oscillation have occurred which introduced frequencies differing somewhat from the desired output frequency. These. additional modes have caused spurious oscillations to be generated thus consuming energy and reducing the efficiency and effectiveness of the device.

' An'object of this invention is to reduce to a minimum the tendency for such spurious oscillations to occur.

Another object is to increase the eiiiciency and effectiveness of a magnetron of the foregoing type. r A still further object is to accomplish the foregoing by a structure which is simple to manufacture and assemble.

- Theforegoing and other objects of this in .vention will be best understood from the folis {lowing description of an exemplification there- ..of, reference being had to the accompanying drawings, wherein:

Fig. 1 is a transverse section of a magnetron embodying my invention, taken along line i- -l the endof one of the anode arms; Figs. 4 and 5 are fragmentary enlarged crosssections taken along the line 4-4 of Fig. 3;

,comprises an envelope 1 which is preferably 1,

. bore M andits adjacent arms form a circuit Fig. 6 is a developed section taken through the ends ofthe anode arms of Figs. 1 and Z' adjathereof a cathode 6 which may be of the indirectly-heated oxide-coated thermionic type. The cathode is supported by a pair of cathode lead-in conductors l and 8 sealed through glass seals 9 and I0 mounted at the outer ends of pipes H and I2 hermetically fastened within the walls of the block 1 adjacent the upper and lower hollow end sections. Light conducting shields 1 and 8' may be supported adjacent the upper and lower ends of the cathode B so as toprevent electron beams from being projected out toward the end caps 2 and 3. A plurality of slots l3 extend radially from the central bore '5, and each of said slots terminates in a circular opening i 4 extending through the bridging portion 4. 'In this way, the anode structure is provided with a plurality of wedge-shaped arms l5-Z2' inclusive, the faces of which cooperate as anode sections with the cathode 6.

When such a magnetron is placed between suit- .able magnetic poles 23 and 24 to create a longicent one side of the strips which interconnect pthe anode arms; and -1Fig. 7 is an enlarged fragmentary cross-sec 'tion taken along line ll of Fig. 1. V

1The magnetron illustrated in the drawings :jmade of a block of conducting material, such as I copper.

This block forms the anodestructure tween the hollow end sections of the block I is located a central bridging-portion 4. Theporwise .of conductive material, such as copper. Be- M lion 4 is provided with a central bore 5 within tudinal magnetic field and. the device is energized, oscillations are .set, up. These oscillations may be led out from the tube by means of a coupling loop 25 extending into one of the cylindrical openings l4 and having one end thereof fastened to the inner wall of said opening. The other end of the coupling loop 25 is connected to a lead wire .28 which passes through a glass seal '21 mounted at the outer end of a pipe 28 likewise hermetically fastened through the wall of the envelope I. An additional conducting pipe, not shown, may be electrically connected to the pipe 28, and form with the wire 26 a concentric line through which the high frequency oscillations generated by the magnetron maybe conducted to a suitable utilization circuit.

Capacitances exist between the side walls of The anode,

predetermined frequency at which the device is to be operated. v w I The device is intended to operate sothat each tuned to the frequency at which each of the other bores and itsadjacent arms oscillate.

It has been found that in magnetrons of this general type, there has been a tendency for oscillations to be produced, not only in accordance with the above desired mode but also in various undesired spurious modes. One particularly troublesome mode is that in which alterhate anode arms form opposite ends of an oscillating circuit extending around the back of a pair of openings I4. As more fully described and claimed in my copending application Serial No. 421,145, filed December 1, 1941, now Patent No. 2,417,789, dated March 18, 1947, this spurious oscillating mode can be substantially eliminated by interconnecting the outer ends of alternate anode arms directly by relative low impedance paths. However, at the extreme high frequency at which such devices are intended to operate, it is difiicult to make such electrical connections of sufiiciently low impedance to reduce such spurious modes to a minimum. In accordance with the present invention such interconnections are made in a novel manner which reduces the impedance of such interconnections to a minimum and thus likewise reduces the spurious oscillations to a minimum.

In order to accomplish the electrical connection referred to above, a pair of conducting straps 2'9 and 30 are fastened at opposite ends of the magnetron structure. These straps are of a good conductive material, such as silver or copper. In order to receive thestrap 29 the upper faces of the anode arms are provided with slots 31' located toward the outer ends of said anode arms. Likewise the lower faces of said anode arms are provided with similar slots 32 to receive the conducting strap 30. Each of the top faces of the anode arms l6, 18, 20 and 22 are provided with a groove 33 extending along the bottom of the slot 31. The strap 29 is provided with a series of spaced tabs 34. As shown in Fig. 6, the spacing between the tabs 34 is such that they contact alternate anode arms, causing the intermediate portion of the strap 29 to pass over the intervening anode arm without coming into electrical contact therewith. The tabs 34 on the strap 29 are received into the grooves '33 on said anode arms l6, 1.8, 20 and 22. The lower strap 30 is likewise provided with tabs 34. Also the lower faces of the anode arms I5, 17, I9 and 21 are provided with grooves 33 at the bottom of the slots 32 and the tabs 34 of said strap 30 are received in said grooves.

In order to assemble the conducting straps with the electrode structure, one of said straps, for example 29, which originally may be stamped out in fiat form, is bent into a circle and dropped into the slots 3| with the tabs 34 fitting into the grooves 33. As shown in Fig. 4 initially there may be a slight clearance between each tab 34 and its associated groove 33 in order that the strap 29 may drop into place easily. In order to fasten the strap 29 in place, a staking tool 35 is used. This staking tool may be cylindrical in shape and is provided with a plurality of pointed prongs 36 which project into each of the slots 3| in which it is desired to fasten the conducting strap 29. Preferably the staking tool 35 is provided with four such prongs for each of the slots in which such fastening is desired. As shown in Fig. 3, such pointed prongs may be used to make a pattern of indentations as indicated at b, c, d and e. The staking tool 35 is then forced in against the structure and as shown in Fig. the metal of the anode arm is forced in against the sides of the tab 34 firmly retaining the strap 29 in-place and establishing intimate electrical contact therewith. Thus by a single operation of the staking tool 35 the strap 29 is securely fastened to' each of the anode arms [6, I8, and 22. It will be noted from Fig. 6 that the tabs 34 are substantially of the same length as the associated anode arm, thus giving a maximum of electrical contact with the strap 29. In order to fasten the strap 30 in place, the structure is inverted, whereupon the strap 30 is fastened in position, exactly the same way as described for the strap 29. The same staking tool may be used since the distances between the slots in which the fastening is to occur is exactly the same for the two straps. Thus the strap 36 is firmly and electrically connected to the anode arms l5, l1, l9 and 2|.

Due to the above structure the alternate anode arms [5, l1, I9 and 2| are directly interconnected by a conductive path of extremely low impedance. Likewise the alternate anode arms l6, I8, 20 and 22 are connected by a conductive path of extremely low impedance. When the device is oscillating in accordance with the desired mode of operation, the voltages on alternate anode arms vary in phase with each other. The above electrical interconnection insures that such an operation shall occur. If there is any tendency for spurious oscillations to occur, a sufficient amount of current flows through the strap interconnections to eliminate or damp out such spurious oscillations. Also it is necessary for the energy of each oscillating loop 14 removed from the coupling loop 25 to be fed to successive oscillating loops and finally to reach that oscillating loop with which the coupling loop 25 is associated. A substantial part of this energ may flow through the strap connectors 25. Thus it will be seen that the strap connectors may carry os cillations which represent energy of substantial magnitude. It will also be noted from Fig. 6 that as each conducting strap passes from one anode arm to which it is connected to an alternate anode arm, it possesses a substantial length of conductor which passes adjacent to the intermediate anode arm. In absence of special precautions this intermediate length of conductor may introduce suiiicient impedance so that the oscillations which flow through it may introduce voltage drops of suificient magnitude to enable spurious oscillations to be generated and thus decease the efficiency of the device. In the present arrangement this impedance is reduced to a minimum by properly selecting the relationship between the dimensions of the conducting strap and of the slot through which it passes. This relationship may be made clear by referring to Fig. 7 in which 01 represents the width of the conducting strap, (either 29 Or 30), D represents the width of the slot 3!, Z represents'the height of the conducting strap, and L represents the depth of the slot 3|. The dimensions are so selected that D is about three times (i and L is about three times I. In a practical embodiment of this invention D was about 70 mils, d was about 20 mils, L was about 60 mils and i was about 20 mils. Such a relationship produced excellent results. With the foregoing relationship the conducting strap as it passes through a slot 3| forms therewith substantially a concentric transmission line which possesses a minimum of impedance for the transmission of ultra high frequency energy therethrough. Theoretically the ideal ratio between D and d and L and Z is 3.32 in which case substantially the maximum efiect of a concentric transmission line is obtained. However, as indicated above deviations from this ideal ratio may be had without unduly affecting the operation. It is desirable that such variation be permitted because variation in the distance between the conducting strap and the slot 3| introduces variations in the capacitance of the adjacent oscillating cavities. This phenomenon is more fully described and claimed in my copending application, Serial No. 425,071, filed December 31, 1941, now Patent No. 2,408,235, dated September 24, 1946. Thus b proper design of this spacing, variation in the sizes of the slots l3 and the cylindrical openings I4 may be compensated for soas to bring the natural frequency of each of the oscillating circuits exactly into resonance with each other at the desired frequency. I

I have found that it is desirable not to close both rings formed by the straps 29 and 30, but to permit at least one of said rings to be interrupted between adjacent ends of the strap when it is bentinto a circle. I have also found that maximum efficiency of operation occurs when the interruption in the ring is locatedat some point between a pair of connecting tabs 34 situated as remote as possible from the coupling loop 25. Although the interruption in a single ring may be suflicient, I have also found that the device operates with substantially the same, if not slightly increased, eificiency when both rings are interrupted as described above. Also from a manufacturing standpoint it is desirable to have both rings interrupted since in such case both rings are identical. In accordance with the above aspect of my invention, the interruption in the strap 29 may occur at the point 31 adjacent the arm l5, as illustrated in Figs. 1 and 6, and the interruption 38 in the strap 30 may occur adjacent the arm 22, as illustrated in Fig. 6. An arrangement of this kind possesses a maximum of efliciency in so far as this aspect of the device is concerned. Sincethe lead-in conductors! and 8 preferably enter'the structure at a point opposite to that at which the loop is located, it will be seen that the interruptions 31 and 38 lie respectively on opposite sides of the plane containing the lead-in conductors I and 8.

l -I have found that when the above connections are'made substantially no spurious modes of oscillations tend to occur. At the same time there appears to be nosubstantial interference with the normal mode of oscillation. I have constructed tubes-in this way which have had a much higher percentage of the output energy concen- .vention is not limited to the particular details as described above as many equivalents will suggest themselvesto those skilled in the art; For example, the conducting strap need not be rectangular in shape. Other shapes would be equally useful provided the principles of my invention are retained. Likewise other anode configurations could be utilized instead of the slot and circular opening arrangement as illustrated herein. Various other equivalents will suggest themselves to those skilled in the art. 7

" What is claimed is:

7 1. An electron discharge device comprising an electrode structure including a cathode and an anode, said electrode structure having a series of loop portions forming capacitances and inductances constituting tuned circuits which are adapted to have set up therein oscillations producing a plurality of in-phase voltage loops, a plurality of predetermined points being located on said electrode structure, said in-phase' voltage loops occurring at said points, and a conductor interconnecting each of said points, said conductor being substantially surrounded by conducting material along a substantial portion of its length, and forming with said conducting material a virtual concentric transmission line.

2. An electron discharge device comprising an electrode structure including a cathode and an anode, said electrode structure having a series of loop portions forming capacitances and inductances constituting tuned circuits which are adapted to have set up therein oscillations producing a plurality of in-phase voltage loops, a plurality of predetermined points being located on said electrode structure, said in-phase voltage loops occurring at said points, and a conductor interconnecting each of said points, said conductor being substantially surrounded by adjacent portions of said electrode structure along a substantial part of its length between each of said points, and forming with said surrounding portions a virtual concentric transmission line.

3. An electron discharge device comprising an electrode structure including a cathode and an anode, said anode having a plurality of electronreceiving portions adjacent said cathode, and a plurality of grooved portions spaced from said electron-receiving portions forming a plurality of inductances which together with the interelectrode capacitances constitute a plurality of tuned circuits which are adapted to have set up therein oscillations producing a plurality of in-phase voltage loops, a plurality of predetermined points each being located adjacent one of said electronreceiving portions, said in-phase voltage loops occurring at said points, and a conductor interconnecting each of said points, said conductor being substantially surrounded by conducting material along a substantial portion of its length, and forming with said conducting material a virtual concentric transmission line.

' 4. An electron discharge device comprising an electrode structure includinge a cathode and an anode, said anode having a plurality of electronreceiving portions adjacent said cathode, and a plurality of grooved portions spaced from,said electron-receiving portions forming a plurality of inductances which together with the interelectrode capacitances constitute a plurality of tuned circuits which are adapted to have set up therein oscillations producing a plurality of in-phase voltage loops, a plurality of predetermined points each being located adjacent one of said electron-receiving portions, said iii-phase voltage loops occurring at said points, and a conductor interconnecting each of said points, said conductor being substantially surrounded by adjacent portions of said electrode structure along a substantial part of its length between each of said points, and forming with said surrounding portions a virtual concentric transmission line.

- 5.An electron discharge device comprising an electrode structure including a cathode and an anode, said anode havinga plurality of electronreceiving portions adjacent said cathode, and a plurality of grooved portions spaced from said electron-receiving portions forming a plurality of inductances which together with the interelectrode capacitances constitute a plurality of tuned circuits'and a conductor interconnecting alternate electron-receiving portions, said conductor being substantially surrounded by conducting material along a substantial portion of its length, and forming with said conducting material a virtual concentric transmission line.

6. An electron discharge device comprising an electrode structure including a cathode andan anode. said anode having a plurality of electronreceiving portions adjacent said cathode, and a plurality of grooved portions spaced from said electron-receiving portions forming a plurality of inductances, and a conductor interconnectingalternate electron-receiving portions, said conductor being substantially surrounded by the anode adjacent the intermediate electron-receiving portions and substantially forming a concentric transmission line with said surrounding anode portions. 7

7. An electron discharge device comprising an electrode having a plurality of arms, each pair of which bounds a cavity and forms an inductance, said pair of arms having juxtaposed surfaces forming a capacitance, said inductances and eapacitances forming tuned circuits which are adapted to have oscillations set up therein during operation, and a conductor interconnec ing alternate arms, a slot formed in each arm between said alternate arms, said conductor pass ing through said slots, the cross-sectional dimensions of each of said slots being of the order of three times the corresponding cross-sectional dimensions of the conductor passing through it.

8. An electron discharge devicescomprising an electrode having a plurality of arms, each pair of which bounds a cavity and forms an induztance, said pair of arms having juxtaposed surfaces forming a capacitance, said inductances and capacitances forming tuned circuits which are adapted to have oscillations set, up therein during operation, a conductor interconnecting alternate arms at one end of said electrode and a. conductor interconnecting the intermediate al ternate arms at the other end of said electrode, a slot formed in said intermediate alternate arms at the first-mentioned end of said electrode, a slot formed in said alternate arms at the secondmentioned end of said electrode, said first-named -conductor passing through said first-named slots;

said second-named conductor passing through said second-named slots, the cross-sectional di-- mensions of each of said slots being of the rd 1" of three times the corresponding cross-sectional dimensions of the conductor passing through it.

9. An electron discharge device comprising an electrode structure including a cathode and an anode having a plurality of arms, each pair of which bounds a cavity and forms an inductance, said pair of arms having juxtaposed surfaces forming a capacitance, said inductances and capacitances forming tuned circuits which are adapted to have oscillations set up therein during operation, said arms being circularly disposed about said cathode, means for leading ofi the oscillations generated by said structure coupled to a predetermined localized portion of. said anode, and a conductor interconnecting alternate arms, except for the alternate arms which are farthest from said predetermined localized portion.

10. An. electron discharge device comprising an electrode structure including a cathode and an anode having a plurality of arms, each pair of which bounds a cavity and forms an inductance, said pair of arms having juxtaposed surfaces forming a capacitance, said inductances and capacitances forming tuned circuits which are adapted to have oscillations set up therein during operation, said arms being circularly disposed about said cathode, means for leading off the oscillations generated by said structure coupled to a predetermined localized portion of said anode, a conductor interconnecting alternate arms at one end of said electrode, and a conduc- 8) tor interconnecting the intermediate alternate arms at the other end of said electrode, said conductors being each interrupted at such points that the pair of alternate and intermediate alternate arms farthest from said predetermined point are not connected.

11. An electron discharge device comprising an electrode structure including a cathode and an anode having a plurality of arms, each pair of which bounds a cavity and forms an inductance. said pair of arms having juxtaposed surfaces forming a capacitance, said inductances and capacitances forming tuned circuits which are adapted to have oscillations set up therein durr ing operation, and a conductor interconnecting alternate arms, each arm to which said conductor is connected having a groove, said conductor having a plurality of tabs received into'said grooves, the material of said anode adjacent said groove being pressed in against said tab to retain said conductor in intimate electrical and mechanical connection with said anode.

12. A magnetron comprising an electrode, structure including a cathode, an anode, and means for producing a magnetic field about said cathode, said electrode structure having a series of loop portions forming capacitances and inductances constituting tune-d circuits which are adapted to have set up therein oscillations producing a plurality of in-phase voltage loops, a plurality of predetermined points being located on said electrode structure, said in-phase voltage loops occurring at said points, and a conductor interconnecting each of said points, said conductor being substantially surrounded by conducting material along a substantial portion of its length, and forming with said conducting material a virtual concentric transmission line.

13. A magnetron comprising an electrode structure including a cathode, an anode, and means for producing a magnetic field aboutsaid cathode, said structure having a seriesof loop portions forming capacitances and inductances constituting tuned circuits which are adapted to have set up therein oscillations producing a plurality of in-phase voltage loops, a plurality of predetermined points being located on said elec-.

trode structure, said in-phase voltage loops occurring at said points, and a conductor interconnecting each of said points, said conductor being substantially surrounded by adjacent portions. of said electrode structure, and forming with said surrounding portions a virtual concentric transmission line along a substantial part of its length between each of said points.

1a. A magnetron comprising an electrode structure including a cathode, an anode having a plurality of arms, each pair of which bounds a cavity and forms an inductance, said pair of arms having juxtaposed surfaces forming; a capacitance, said inductances and capacitances forming tuned circuits which are adapted to have oscillations set up therein duringopera tion, means for producing a magnetic field about said cathode, and a conductor interconnecting alternate arms, a slot formed in each arm between said alternate arms, said conductor passing through said slots, the cross-sectional dimensions of each of said slots being of the order of three times the corresponding cross-sectional dimensions of the conductor passing through it.

15. An electron-discharge device comprising: a cathode; an anode structure provided with a plurality of anode arms spaced from said cathode; each pair of adjacent anodearms, together with that portion of said anode structure lying therebetween, defining a cavity resonator; and a conductor interconnecting alternate anode arms;

said conductor being substantially surrounded,

along a substantial portion of its length, by conducting materialand forming, with said conducting material, a transmission line. 7

16. An electron-discharge device comprising:

' a cathode; an anode structure provided with a plurality of anode arms spaced from said cathode; each pair of adjacent anode arms, together withithat portion of said anode structure lying therebetween, defining a cavity resonator; and a conductor interconnecting alternate anode arms;

said conductor being substantially surrounded, along a substantial portion of its length, by portions of the intervening anode arms, and formof aclosed circuit therethrough. 19. An electron discharge device having a plurality of anode members extending radially from a central space defined by said members, a cathode adjacent said anode segments for supplying electrons within said central space, said anode members having slots in one end thereof, and concentric ring-shaped strapping elements having extensions normal to the plane of the element, the extensions of one of said ring-shaped strapping elements contacting alternate anode members within the slots thereof, and the extensions on another ring-shaped strapping element lying within the slots of and connecting the remaining anode members together.

"20. A structure for a magnetron-type discharge device including a first electrode comprising a circular array of electrode sections mutually spaced apart and defining cavity resonators therebetween, a second electrode spaced from said array of electrode sections andfproviding a source of electrons in the interelectrode space, magnetic means adjacent said electrodes for producing a magnetic field in said interelectrode space to control the movement of said electrons to cause excitation of said first electrode, and a system of conductive connections adjacent each face of said first electrode, said faces being spaced apart along the length of said second electrode, each system of connections including a conductive member contacting alternate electrode sections and passing freely through intervening electrode sections, material of said intervening electrode sections, in the regions adjacent said conductive member, intervening between said conductive member and said electrode space.

charge device including an electrode having an opening therein and having a plurality of cavity resonators about said opening and dividing said electrode into a plurality of electrode sections,

a second electrode in said opening and providing "a source of electrons in the interelectrode space, jm'agnetic means in proximity to said electrode sections for controlling the movement of'said electrons in said interelectrode space to produce high frequency excitation of said first electrode, and a system of conductive connections adjacent each face of said first electrode, each system of connections including a conductive member contacting alternate electrode sections and passing freely through intervening electrode sections, material of said intervening electrode sections, in the regions adjacent said conductive member, intervening between said conductive member and said electrode space.

22. A structure for a magnetron-type discharge device including a first electrode-having an opening therein and having a plurality of cavity resonators about said opening and dividing said electrode into a plurality of electrode sections, a second electrode positioned in said opening and providing a source of electrons in 21. A structure for a magnetron-type disrespect to the electrode structure.

the interelectrode space, magnetic means in proximity to said electrode for controlling the movement of. said electrons in said interelectrode space toproduce high frequency excitation of said first electrode, and a system of conductive connectionson each face of said first electrode,

each system of connections including connections between alternate electrode sections, the

conections of each of said systemscomprising conductors which are readily adjustable with respect to the surface of the first electrode. Y

23; An electrode structure for a high frequency device comprising a plurality of electrode sec.- tions mutually spaced apart providing cavity resonators therebetween and adapted to be excited at high frequency, said sections having face portionsfor confining the spacecharge of the device and means conductively connecting predetermined electrode sections together inproximity to said face portions to separatethe natural modes of oscillation of said structure and to stabilize the operation thereof when said electrode structure is excited for operationat a particular frequency, said means being adjustable with 24. An electrode structure comprising a plurality of electrode sections mutually spaced apart providing cavity resonators therebetween and adapted. to be excited at high frequency, and means conductively connectingpredetermined electrode sections together to separate the natural modes of oscillation of said structure and to, stabilize the operation thereof whensaid electrode structure is excited for op-erationat a particular frequency, said means comprising conductive loops which are readily bendable.

when said cathode is electron-emissive, said structure having surfaces adjacent to which an alternating electric field exists during operation, which surfaces comprise elements separated by gaps,said resonators constituting a system which is cap-able of oscillating in a plurality of diilerent modes atthe frequencies appertaining thereto, in one of which modes one group of less than all of said separated elements oscillate in phase with each other, and electrical connections between members of said group, additional to and exclusive of the above-mentioned interconnections between all parts of said structure, said 'is capable of oscillating in a plurality of different modes at the frequencies appertaining thereto, in one of which modes certain of said separated surface portions oscillate in phase with each other and certain other of said portions oscillate in phase with each other, and means for electrically connecting together some of said surface portions which thus oscillate in phase, additional to and exclusive of the above-mentioned interconnections between all of said resonators, said connecting means including a conductive member contacting said surface portions which thus oscillate in phase and passing freely through the remaining surface portions, material of said last-named surface portions, in the regions adjacent conductive member, intervening between said conductive member and said cathode.

27. A high-frequency magnetron device comprising a cathode, a plurality of resonators in juxtaposition thereto, all conductively interconnected, and electrically coupled when in operation, and constituting a system which is capable of oscillating in a plurality of different modes at the frequencies appertaining thereto, said resonator systemhaving surfaces adjacent to which an alternating electric field exists during operation, comprising portions separated by gaps, certain of said separated surface portions constituting one group oscillating in phase with each other but out of phase with other of said surface portions constituting a second group which oscillate in phase with each other during operation of said system in one of said modes, and means additional to and exclusive of the abovementioned interconnections between all of said resonators for electrically coupling together some of the members of said first group and for electrically coupling together some of the members of said second group, said coupling means including a pair of conductive members one of which contacts said some of the members of said first group and passes freely through the members of said second group, and the other of which cont-acts said some of the members of said second group and passes freely through the members of said first group, material of said members of both said groups, in the regions adjacent said conductive members, intervening between said conductive members and said cathode.

28. A high-frequency magnetron device comprising a cathode, a plurality of resonators in juxtaposition thereto, all conductively interconnected, and electrically coupled when in operation, and constituting a system which is capable of oscillating in a plurality of different modes at the frequencies appertainingthereto, said resonator system having surfaces adjacent to which an alternating electric field exists during operation, comprising portions separated by gaps,

12 certain of said separated surface portions constituting one group oscillating in phase with each other but out of phase with other of said surface portions constituting a second group which oscillate in phase with each other during operation of said system in one of said modes, members of said first group alternating with members of said second group, and means additional to and exclusive of the above-mentioned interconnections between all of said resonators for electrically coupling together some of the members of said first group and for electrically coupling together some of the members of said second group, said coupling means including a pair of conductive members one of which contacts said some of the members of said first group and passes freely through the members of said second group, and the other of which contacts said some of the members of said second group and passes freely through the members of said first group, material of said members of both said groups, in the regions adjacent said conductive members, in-

tervening between said conductive members and said cathode.

29. A high-frequency magnetron device, comprising a cathode, a plurality of resonators disposed circumferentially around said cathode, all conductively interconnected, and electrically coupled when in operation, and constituting a system which is capable of oscillating in a pluralityof different modes at the frequencies appertaining thereto, said resonator system having surfaces adjacent to which an alternating electric field exists during operation, comprising portions separated by gaps, certain of said separated surface portions constituting one group oscillating in phase with each other but out of phase with other of said surface portions constituting a second group which oscillate in phase with each other during operation of said system in one of said modes, and means additional to and exclusive of the above-mentioned interconpasses freely through the members of said second group, and the other of which contacts said some of the members of said second group and passes freely through the members of said first group, material of said members of both said groups, in the regions adjacent said conductive members, intervening between said conductive members and said cathode.

30. A high-frequency magnetron device, comprising an anode member all parts of which are conductively interconnected, having an axiallyextcnding bore therein and having a plurality of resonator cavities therein disposed about and opening into said bore, the openings from said cavities into said bore serving to couple the said cavities and to divide the wall of said bore into segments, a cathode axially positioned in relation to said bore, said segments comprising two groups the members of which alternate with members of the other, means for electrically coupling together only members of one group, and means for electrically coup-ling together only members of the second group, both of said means being additional to and exclusive of the abovementioned interconnections between all partsof said anode member, said coupling means including a pair of conductive members one of which contacts said members of said first group and passes freelyithrough said members of said second group, and the other of which contacts said members of said second group and passes freely through said members of said first group, material of said members of both said groups, in the regions adjacent said conductive members, intervening between said conductive members and said cathode.

31. A high-frequency magnetron device, comprising an anode member all parts of which are conductively interconnected, havin an axially extending bore therein and having a plurality of resonator cavities therein disposed about and opening into said bore, and said member also having transverse end spaces, into each of which said cavities and bore open, the openings from said cavities into said bore serving to couple said cavities and to divide the wall of said bore into segments, a cathode axially positioned in relation to said bore, said segments comprising two groups the members of which alternate with 1 members of the other, means for electrically coupling together members of the firstgroup and means for electrically coupling together members of the second group, both of said means being additional to and exclusive of the, abovementioned interconnectionsbetween"all parts of said anode member, said coupling means including a pair of conductive members one of which contacts said members of said first group and passes freely through said members of said second group, and the other of which contacts said members of said second group and passes freely through said members of said first group, material of said'members of both said groups, in the the regions adjacent said conductive members, intervening between said conductive members and said cathode.

. 32. An electron discharge device comprising an electrode structure including a cathode and an anode, said electrode structure having a configuration constituting capacitance and inductance elements forming circuits which are adapted to have oscillations set up therein, said oscillations being all of the same frequency, a plurality of predetermined points on said electrode structure at which in-phase voltage loops of said oscillations occur, and relatively short conducting means directlyinterconnecting said points, portions of said electrode structure intermediate said interconnected points intervening between said conducting means and said cathode.

33. An electron discharge device comprising a cathode and an anode, said anode having a plurality of electron-receiving portions adjacent said cathode, and a plurality of grooved portions spaced from said electron-receiving portions forming a plurality of inductances which together with theiinterelectrode capacitances constitute a plurality of tuned circuits adapted to oscillate at substantially the same frequency, and relatively "short conducting means directly interconnecting alternate electron-receiving portions, parts of intervening electron-receiving portions shielding parts of said conducting means from said cathode.

34. A magnetron comprising an electrode structure including a cathode and an anode,

means for producing a magnetic field about said cathode, said electrode structure having a configuration constituting capacitance and inductance elements forming circuits which are adapted to have oscillations set up. therein, said oscillations being all of the same frequency, a plurality of predetermined points on said electrode structure at which in-phase voltage loops of said oscillations occur, and relatively short conducting means directly interconnecting said points, portions of said electrode structure intermediate said interconnected points intervening between said conducting means and said cathode.

35. A magnetron comprising a cathode and an anode, means for producing a magnetic field about said cathode, said anode having a plurality of electron-receiving portions adjacent said cathode, and a plurality of grooved portions spaced from said electron-receiving portions forming a plurality of inductances which together with the interelectrode capacitances constitute a plurality of tuned circuits adapted to oscillate at substantially the same frequency, and relatively short conducting means directly interconnecting alternate electron-receiving portions, parts ofintervening electron-receiving portions shielding parts of said conducting means from said cathode.

i 36. An electron discharge device having a plurality of spaced anode elements defining a chamher, a cathode for supplying electrons within said chamber, cavity resonators coupled between adjacent anode elements and opening into said chamber, and wave transmission means for coupling said resonators together, said coupling means including substantially a concentric transmission line extending between and opening into adjacent resonators.

37. An electron discharge device having an anode block of solid conducting material, said block having an axially directed central cham-. her, and cathode means for supplying electrons within said chamber, saidanode block having radially directed slots extending from said chamber and forming therebetween anode elements defining said chamber and cfavity resonators connecting adjacent anode elements, said cavity resonators being open to the central chamber, said block having substantially a concentric transmission line connecting adjacent cavity resonators intermediate the inner and outer ends thereof.

PERCY L. SPENCER.

REFERENCES crrnn The following references" are of record in the file of this patent: 1

UNITED STATES PATENTS Number Name Date 2,270,777 Von Baeyer Jan. 20, 1942 FOREIGN PATENTS Number Country Date 215,600 Switzerland Oct. 16, 1941 509,102 Great Britain July 11, 1939 OTHER REFERENCES Proc. 1. R. E. vol. 32, No. 3, March 1944. 

